Apparatus for determining ranges by means of sound waves



July 27 1926. 1,593,972

H. c. HAYES APPARATUS FOR DETERMINING RANGES BY MEANS OF SOUND WAVES Filed June 30, 1924 2 Sheets-Sheet l HARVEY CHAYES July 27, 1926. 1,593,972

H. c. HAYES APPARATUS FOR DETERMINING RANGES BY MEANS OF SOUND WAVES Filed June 30, 1924 2 Sheets-Sheet 2 gum/P01, f-DARVEY CHAYES Q Q Q Patented Jill 21, 1926;

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Application filed June '30, 1924. Serial in. 728,428.

My invention relates generally to a sys: 'tem for determining ranges by -means of sound waves, but ,more particularly to a means for eliminating the direct signals and collecting the reflected signals.

A further object of my invention isthe employment, in an apparatus for determin: ing ranges by means of sound waves,'of a unit consisting of a plurality of transmitters and a unit consisting ofa plurality of receivers; With these and other objects in view my invention can be best understood by reference to the accompanying drawings in which Figure 1 is a schematic drawing of my invention and Fig. 2 is a diagrammatic sketch showing the relatign between the intensity of the received souiid Plead the direction with respect to the line f Referring to Figure 1, 'P is a unit consisting of two or more like transmitters and R is a unit consisting of two or more like.- recelvers, whereln 1 and 2 are two l1ke transmitters and 3 and arej-two like receivers, the two units T and being mounted along an apipg'oximately straight line A'-A.

for the reason that the direction of the 'two vectors will diifer b 180 degrees. And if the intensity furnis ed. by each transmitter at any point on this line were equal the.

vector sum would be exactly zero and no sound would be heard on a receiver placed at that point. For all points ofi of this line the vecto'r sum""cannot be zero because the two vectors are not-displaced 180 degrees with'respect .toone another and hence the direct sound from the transmitters will be heard on a receiver placed at such a point.

From the above it is obvious that neit \er receiver (3) nor (4) responds with much inv tensity to the direct sound from the two transmitters (1) and (2), but that each will respond to the echo of the sound as reflected at point (0) on the sea-bottom or other reflecting surface unless this point of reflection happens to be located on the line (AA), for we may for convenience considerthe source as points (1' which are the image of (1) an (2) in the reflecting plane. Since the direction of the sound path from these transmitters to the receivers is not parallel with the line and (2') (AL-A) the vector sum cannot be zero.

Thus it will be seen that the two transmitters located a half wave-length apart and a single receiver placed at some point on -the straightline passing through. the two resensitive to' the direct sound from the transmitters but sensitive in general to the echoes of the signals from the firansmitters. If, however, the two eceivers 4 are alike ceivers gives a combination that is very inand are spaced wave length apart along the line (AA) and are connected in series or in parallel so that the output from the two will be equal to the vector sum, then the pair give practically zero'response to the direct sound from the two transmitters and respond with about twice the sensitivity of a single receiver to the echoes. Thus the fcombin ation of two transmitters ahd two receivers is to be preferred to two transmitters and a single receiver. And it becomes obvious that some advantage would be given by employing several transmitters and several receivers, the spacing along the-line (AAz,) being made ual to an preferred.

Finally it is to be noticed that a s' le .transmitter and two equal receivers loca ed.

odd number of half wav -lengt s, but in general one half wavezlength" spacing being alon the same'straight line vwith the spacing etween the two receivers made equal to a half wave-length of'the transmitted sound (or an odd number'of half wavelengths) and the receivers 'connecte'dfin series or parallel so that the combined output will be equal to the vector sum will be veryqv insensitive to the direct sound from the transmitter but will respond to the echo so long as the direction of the echo is not parallel with the line passing through the transmitter and receivers/ Having described my invention I claim .1. In .apparatus for rangin by direct sound waves and echoes derive therefrom, the combination of agpair of transmittin devices, a pair of receiving devices locate in a plane passing through andcooperating .sqlind waves whereby the receivers remain unresponsive to d1rect-waves but are readily aflected by the resulting echoes.

. 2-. In apparatus for ranging by sound waves includinga plurality of transmitters,

the method of gaining null response of direct waves at a point positioned in the a plane passing through ,said transmitters which consistsrin spacing the transmitters apart a distance substantially equal to one,

'half a wave length of said-sound waves.

3. In a system for determining distances by sound waves including a air of transmitting devices and a pair 0 receiving devices -operatively axociated therewith the method of gaining maximum response to said waves which consists in spacing apart the devices comprising each respective pair,

a distance substantially equal to a sub-multiple of a wave length of said sound waves.

' HARVEY C. HAYES. 

